The term addition agent is generally used to describe any of the materials added to molten steel to effect a desirable composition or property. Addition agents are also widely used in non-ferrous alloys to affect the composition or property of the alloy. Characteristic of these desirable ends are deoxidation of the molten metal, control of grain size, increased corrosion resistance, increased heat resistance and improvement of the mechanical and physical properties, to name but a few.
The more common addition agents include aluminum, boron, calcium, chromium, niobium, manganese, molybdenum, nitrogen, phosphorus, selenium, silicon, tantalum, titanium, tungsten vanadium, and zirconium; these addition agents are generally added as an alloy with iron and are therefore referred to as ferroalloys. Others are added as pure metals, such as aluminum, calcium, cobalt, copper, manganese and nickel. Still others are added as oxides, such as molybdenum, nickel and tungsten. Some rare-earth alloys are also used in special instances.
Addition agents may be added with the charge in the furnace, in the molten bath near the end of the finishing period, in the ladle, or in the molds. Timing of the alloy addition depends upon the effect addition will have on the temperature of the molten metal, the ease with which the addition agent goes into solution, susceptibility of the addition agent to oxidation and formation and elimination of reaction products.
The instant invention is directed to composition used in compacting the addition agent for introduction into the metallurgical operations, such as steel manufacturing. Compaction has variously been carried out by briquetting, extruding, molding, pelletizing, or tabletizing the addition agent can more easily be handled and fed into the furnace or other metallurgical stage than the uncompacted addition agent.
Both organic and inorganic binding additives have been incorporated with addition agents to assist in this compaction stage. Generally, compaction has carried out employing petroleum based pitch binders of which asphalt pitch appears to be the industry's preference. Unfortunately, these petroleum based pitch binders are often characterized by high solid failure rates, low abrasion resistance and a tendency to produce high levels of dust during the dry mixing operations. Although the industry has experimented with other binders, such as tall oil pitch as described in U.S. Pat. No. 3,814,789; dextrin as described in U.S. Pat. No. 2,726,152; and alcohols as described in U.S. Pat. No. 3,340,024, these binders have either proven too expensive or lacking the requisite properties to be effective in compaction.
Accordingly, the industry continues in its need for a novel binder that can at once overcome the difficulties inherent in petroleum based binders and yet exhibit the properties necessary to be effective in compaction.